Hypoxia-Activated O6-Benzylguanine Prodrugs

缺氧激活的 O6-苄基鸟嘌呤前药

• 批准号: 7129307
• 负责人: ALAN CLAYTON SARTORELLI
• 金额: $ 29.29万
• 依托单位: YALE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-07-01 至 2009-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7129307
• 关键词: guanine; hypoxia; neoplasm /cancer; prodrugs; proteins; tissues

DESCRIPTION (provided by applicant): Alkylating agent prodrugs that chloroethylate the O-6 position of DNA guanine include Cloretazine, an agent currently in Phase III clinical trial; BCNU, an FDA approved clinically used nitrosourea; and KS119W, a water-soluble sulfonyl hydrazine prodrug selectively activated in hypoxic cells of solid tumors. This DNA lesion is susceptible to repair by O6-alkylguanine-DNA alkyltransferase (ACT), a protein that transfers alkyl groups from the O-6 position of guanine to the ACT molecule. This action represents the primary mechanism of tumor and host tissue resistance to Cloretazine, BCNU, and KS119W. One of the most potent known inhibitors of ACT is O6-benzylguanine (06-BG), which reacts with ACT to form S- benzylcysteine in the active site of the protein. As a result, O6-BG depletes ACT and increases the sensitivity of tumor and host cells to Cloretazine, BCNU and KS119W. Non-toxic doses of systemic O6-BG have been shown in patients to deplete the ACT content of tumors. This action, however, also sensitizes host tissues to BCNU used in combination, necessitating an 80% decrease in the dosage of this agent because of myelosuppression, leading to an ineffective level of BCNU. The Specific Aims of this application are the (a) design and synthesis of O6-BG prodrugs activated selectively by reducing enzymes in hypoxic cells of solid tumors, thereby selectively depleting tumors of AGT while sparing oxygenated normal tissues; (b) evaluation of pretreatment of hypoxic and oxygenated tumor cells with O6-BG prodrugs in vitro followed by Cloretazine, BCNU, and KS119W; (c) evaluation in vivo of these combinations against a variety of transplanted human tumors containing high levels of AGT activity; and (d) pharmacological and biochemical studies of the mechanism of action of synthesized prodrugs. The primary overall objective is the selection of an O6-BG prodrug for clinical development to use in combination with BCNU, Cloretazine and KS119W. The O6-BG prodrug selected should deplete AGT selectively in solid tumors, thereby permitting use in sequential combination at close to full therapeutic dosage of a chloroethylating agent without increased myelosuppression or toxicities to other normal tissues. The expectation is that solid tumors, resistant to the cytotoxic actions of Cloretazine, KS119W and BCNU because of constitutively high levels of AGT, will be selectively depleted of the resistance inducing protein by pretreatment with the O6-BG prodrug, resulting in conversion of chloroethylating agent resistant neoplasms to drug sensitive ones, thereby increasing the spectrum of malignancies that may benefit from Cloretazine, KS119W, and BCNU.

描述（由申请人提供）：氯乙酯O-6位置DNA鸟嘌呤的烷基化剂前药包括Cloretazine，Cloretazine是目前正在III期临床试验中的药物； BCNU，FDA批准了临床使用的硝酸盐；和KS119W是一种在实体瘤的低氧细胞中选择性激活的水溶性磺酰基氢氮。该DNA病变易于通过O6-烷基鸟嘌呤-DNA烷基转移酶（ACT）修复，该蛋白将烷基从鸟嘌呤的O-6位置转移到ACT分子。该作用代表了肿瘤和宿主组织抗锁甲嗪，BCNU和KS119W的主要机制。最有效的ACT抑制剂之一是O6-苯二唑烷（06-BG），它与ACT反应形成蛋白质活性部位的二苯甲酰半胱氨酸。结果，O6-BG耗尽并增加了肿瘤和宿主细胞对氯酸，BCNU和KS119W的敏感性。已显示患者的无毒剂量的全身O6-BG耗尽肿瘤的ACT含量。然而，这一动作还使宿主组织与用于组合使用的BCNU敏感，因此由于骨髓抑制，该药物的剂量需要降低80％，导致BCNU水平无效。该应用的具体目的是（a）通过减少固体肿瘤低氧细胞中酶选择性激活的O6-BG前药的设计和合成，从而选择性地耗尽了AGT的肿瘤，同时保留了含氧正常组织； （b）在体外用O6-BG前药对低氧和氧化肿瘤细胞进行预处理的评估，然后是氯吡嗪，BCNU和KS119W； （c）对这些组合的体内评估，以对各种含有高水平AGT活性的移植人类肿瘤进行评估； （d）合成前药作用机理的药理和生化研究。总体整体目标是选择用于与BCNU，Cloretazine和KS119W结合使用的临床开发的O6-BG前药。所选的O6-BG前药应在实体瘤中有选择地耗尽AGT，从而允许在接近完全治疗剂量的氯乙基剂的完整治疗剂量中使用，而不会增加对其他正常组织的骨髓抑制或毒性。人们期望的是，由于组成型AGT的组成型高度高，固化性对氯嗪，KS119W和BCNU的细胞毒性作用具有抗性，将通过使用O6-BG预处理抗抗性蛋白的耐药性诱导蛋白质，从而耗尽O6-bg的预处理，从而导致对氯乙基的抗抑制剂的抗抑制剂，从而使抗抑制剂的耐药性耐药性耐药性耐药性耐药性。可能受益于克里替嗪，KS119W和BCNU的恶性肿瘤。